Alvis Leonides Major Explained

The Alvis Leonides Major is a British air-cooled 14-cylinder radial aero engine developed by Alvis from the earlier nine-cylinder Leonides.^[1]

Design and development

In 1951 Alvis started development of a 14-cylinder, two row radial of 1,118 cu in (18.3 L) displacement, based on the Leonides. Certification covered the Mk. 702/1 for aeroplanes at 875hp and the 751/1 for helicopters at 850hp. The only numerous model of the Major was the Mk. 755/1, a medium supercharged, de-rated, obliquely mounted direct-drive and fan cooled engine fitted to the Westland Whirlwind Mks. 5, 6, 7 and 8.^[2]

Variants

Data from:British Piston Engines and their Aircraft.^[3]

Leonides Major 702/1

for aeroplanes, also known as A.LE.M.1-1 in Air Ministry

Leonides Major 751/1

for helicopters, also known as A.LE.M.1-2

Leonides Major 755/1

for helicopters in a 35° canted mounting, also known as A.LE.M.1-6 and as Mk.155 in civil aircraft

Leonides Major 755/2

for helicopters in a vertical mounting, also known as A.LE.M.1-6 and as Mk.160 in civil aircraft

Applications

Bristol Type 173 Mk3 – 2x 755/1 (Mk.155) ; 2x 755/2 (Mk.160)
Handley Page HPR.5 Herald – four 702/1
Westland Whirlwind 1x 755/1 (Mk.155) or 1x 755/2 (Mk.160)

Notes and References

Book: Gunston. Bill. World encyclopaedia of aero engines. 1989. P. Stephens. Wellingborough. 1-85260-163-9. 13. Fully rev. 2nd.
Lumsden 2003, pp.60-61.
Book: Lumsden, Alec . British Piston Engines and their Aircraft . 2003 . Airlife Publishing . Marlborough, Wiltshire . 978-1-85310-294-3 . 60–61.